I agree that having some burn mechanics would go a long way already to stabilize the Steem price. This still doesn't solve the issue that there is little to no reasons to power up and hold a lot of SP these days (at least for average users). When I started on Steem a few years back, you really needed SP to do better on the platform. Right now with all the upvotes coming from the Dapps & Tribes (Steemmonsters, Actifit, Drugwars, esteem, 3Speak, Dtube, PAL, SPORTS, ...) there is almost no difference to how much Steem you can earn/mine between having 100SP which gives you all the RC you need and having 10k SP.
How about this for an idea: If all the DAPPS linked their upvotes directly to the SP someone has giving bigger upvotes to bigger SP holders in a fair way there would be an actual reason to power up and at the same time cut out a lot of abuse since it's easy to just make a new account and start farming all the free dapp upvotes. I honestly want to power up more but I see no reason currently and all I see is people powering down and dumping their steem for steemmonsters cards, different steem-engine tokens, ...
Looking at the numbers there seems to be a connection between dapps / tribe tokens and the price of Steem that continues to go down. What Steem needs is good reasons to hold SP along with some systematic burning mechanics it could do wonders for the STEEM price getting it back into a positive spiral.